In an optical network communications system, photoelectric conversion components have certain requirements for the strength range of input light. If the strength of input light exceeds a specific range, the network will be abnormal. Network maintenance personnel may detect powers of optical signals, determine strength of input light according to the power of optical signals, and take corresponding measures for intervention.
At present, two methods for detecting a power of an optical signal are available, including:
Method 1: When a receiver converts a received optical signal and outputs an output signal, separate a direct current signal from the output signal, convert the direct current signal into an analog voltage signal, convert the analog voltage signal into a digital signal, and calculate a power of the optical signal according to the digital signal.
Method 2: When a receiver converts a received optical signal and outputs an output signal, separate an alternating current signal from the output signal, convert the direct current signal into a radio frequency direct current voltage signal through a TIA (Transimpedance Amplifier, transimpedance amplifier), convert the radio frequency direct current voltage signal into an analog voltage signal, convert the analog voltage signal into a digital signal, and calculate a power of the optical signal according to the digital signal.
It should be noted that: after the receiver receives the optical signal, it converts the optical signal into a photogenerated current signal. The photogenerated current signal includes a direct current photogenerated current signal and an alternating current photogenerated current signal. In addition, the receiver itself will produce a penetrating current signal with weak signal strength, and the penetrating current signal is a direct current signal. Therefore, the separated direct current signal includes the direct current photogenerated current signal and penetrating current signal, and the separated alternating current signal includes the alternating current photogenerated current signal.
During the implementation of the present invention, the inventor discovers that the prior art has at least the following problems:
In the method 1, when the optical signal is weak, the percent of the penetrating current signal included in the separated direct current signal is large, so that the error of the calculated power of the optical signal is large.
In the method 2, the TIA has a saturation point. When the optical signal is strong, the strength of the separated alternating current signal exceeds the saturation point of the TIA. The strength of the radio frequency direct current voltage signal output by the TIA remains unchanged when the saturation point of the TIA is reached. As such, when the optical signal is strong, the error of the calculated power of the optical signal is large.